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Armour Thyroid Side Effects & Adverse Reactions (List)

Armour Thyroid is a porcine-derived thyroid extract manufactured by Actavis Inc. (formerly by Forest Laboratories, Inc.) for the treatment of hypothyroidism.  Unlike synthetically engineered thyroid medications (e.g. levothyroxine), Armour Thyroid is completely natural, and as a result, is thought (by some users and professionals) to be safer and more biologically compatible with humans.  Additionally, many patients with hypothyroidism that are unable to tolerate synthetic thyroid replacement therapies often find that Armour Thyroid causes fewer side effects.

However, not everyone treated with Armour Thyroid considers it an optimal intervention and/or finds it tolerable. In fact, the American Association of Clinical Endocrinologists goes as far as to advise against the usage of Armour Thyroid (and other forms of thyroid extracts) for the treatment of hypothyroidism due to the fact that it may pose greater risk of serious side effects and adverse reactions than traditional treatments.  Since it is “natural,” it has never gone through the rigorous FDA approval process and its long-term safety remains questionable.

Some speculate that unwanted side effects may be common among Armour Thyroid users for numerous reasons including: ratio of T4 to T3 at 4:1 (differing from the normative 11:1 ratio in humans, possibly leading to abnormally high T3), lack of randomized-controlled trials (especially over a long-term), and possible inter-batch variability.  If you’re experiencing side effects from taking Armour Thyroid, realize that you’re not alone.  While some side effects are to be expected (as a normal course of treatment), if side effects interfere with your ability to function, discontinuation may be warranted.

Armour Thyroid Side Effects & Adverse Reactions (List)

Although Armour Thyroid is completely natural, many consumers mistakenly assume that its “natural” status equals safer and better.  For certain users, Armour Thyroid may be better tolerated than synthetic compounds, while in other cases it may provoke more adverse effects.  Below is a compilation of side effects and adverse reactions experienced among Armour Thyroid users.

Realize that the severity and number of side effects you experience will be subject to interindividual variation.  One person may take Armour Thyroid and experience minimal and/or no noticeable side effects, while another may be unable to continue treatment due to poor tolerability.  A few of the most common side effects associated with Armour Thyroid include: headaches, joint pain, moodiness, weight changes, and hair loss.

Allergic reactions: In rare cases, patients may experience severe adverse reactions when taking Armour Thyroid.  Inability to tolerate Armour Thyroid may lead you to: develop a rash (possibly widespread or localized), feel itchy (constantly clawing your skin), and/or notice that various body parts are literally swollen.  Anytime you suspect that you’ve experienced an allergic reaction, immediate medical attention is recommended.

While allergic reactions are not considered common, they can occur.  Additionally, allergic reactions are not always immediately noticeable.  Some individuals may develop an allergic reaction after years of Armour Thyroid usage – possibly resulting from changes in the particular formulation and/or product quality.  All users should be cognizant of possible allergies to desiccated thyroid extracts.

Anxiety: Upon starting treatment with Armour Thyroid, you may experience a low-grade anxiety and/or nervousness, leading to internal discomfort.  In some cases, anxiety associated with Armour Thyroid treatment is a transient side effect.  As you adjust to the increase in neurophysiological stimulation being provided by the medication, your anxiety may subside.

In other cases, anxiety may continue to worsen throughout treatment.  Anxiety may be most severe if you’re receiving too much thyroid hormone such as from an abnormally high dose of Armour Thyroid.  This may lead you to experience severe anxiety to the point of panicking and other physical symptoms of anxiety such as muscle tension, palpitations, and sweating.

Brain fog: Correction of hypothyroidism with properly-dosed Armour Thyroid usually ameliorates brain fog or clouded thinking.  However, among some individuals, even proper doses of Armour Thyroid may interfere with their ability to think clearly.  If after taking Armour Thyroid you feel depersonalized, are unable to organize your thoughts, and/or feel as if the you’ve transformed you into someone with an attentional deficit – you’re not alone.

A small percentage of people report “fuzzy” or foggy thinking during treatment, which may be accompanied by depersonalization or dissociation.  Exacerbation of brain fog may impair your quality of life by affecting job performance, productivity, and social engagement.  This side effect should be discussed with a medical professional if experienced.

Cognitive deficits: Many individuals with hypothyroidism have a difficult time performing cognitively-demanding tasks.  This is because when concentrations of T4 and T3 are suboptimal, neurological performance generally suffers.  Administration of Armour Thyroid is believed to reverse hypothyroidism-induced cognitive deficits, possibly to a greater extent than synthetic interventions such as levothyroxine.

Unfortunately, a subset of Armour Thyroid users have reported that their cognitive performance worsens while taking the medication.  Even if TSH, FT4, and FT3 levels are perceived as normal by an endocrinologist or medical doctor, it is necessary to acknowledge that Armour Thyroid may impair cognitive function.  Impairment of cognitive function may have deleterious implications for many aspects of life, particularly occupational and scholarly pursuits.

Chest pain: Experiencing chest pain while taking Armour Thyroid is considered a severe adverse reaction.  If you notice chest pain at any point throughout treatment, it is necessary to seek emergency medical attention.  Armour Thyroid can affect cardiac function, which could trigger a heart attack – especially among those diagnosed with cardiovascular disease.

While the likelihood of a treatment-induced heart attack is low, it is important to regularly monitor heart function for the sake of your safety.  In some cases, chest pain may result from tension associated with increased neurophysiological arousal.  Chest pain may be most likely among individuals taking too high of an Armour Thyroid dose.

Depression: Although many individuals taking Armour Thyroid report that their mood actually improves throughout treatment, some notice that they become increasingly depressed.  It is unclear as to how Armour Thyroid may cause depression as a side effect.  Some speculate that administration of the drug alters neural activation and densities of monoamines in particular regions.

Those with an underlying neuropsychiatric disorder (e.g. bipolar disorder, major depression, etc.) may be more prone to bouts of depression as a side effect of Armour Thyroid; it could be that their neurochemistry is more sensitive to any neurophysiological stimulus.  That said, depression isn’t a “common” side effect of Armour Thyroid.  In fact, most users notice an improvement in mood following treatment or a reversal of depression as induced by hypothyroidism.

Diarrhea: Taking Armour Thyroid may affect gastrointestinal function, possibly causing distress, upset stomach, and ultimately diarrhea.  If you experience diarrhea from Armour Thyroid, it may be that you’re taking too high of a dose.  Higher-than-average dosages can expedite the shuttling of ingested food through the body, leading to increased frequency of bowel movements and loose stools.

If a professional has verified that you’re taking the optimal dosage of Armour Thyroid, yet you’re still experiencing diarrhea, you may need to consider utilizing an over-the-counter agent such as Imodium to mitigate this side effect.  Understand that for some individuals, diarrhea will be a mild and temporary side effect that subsides after a few weeks of treatment.  If the diarrheal response is severe, it may be a sign that you’re unable to tolerate Armour Thyroid.

Dizziness: A relatively common side effect of Armour Thyroid is dizziness.  Don’t be surprised if after initiating treatment, you feel exceptionally dizzy.  For most users, some dizziness will occur during the first few weeks of treatment, but usually won’t be severe enough as to interfere with daily functioning.

If you feel extremely dizzy (as if the walls are spinning) and are unable to function, this side effect should be discussed with your doctor.  Mild dizziness is a common side effect of any thyroid replacement therapy.  As your neurophysiology continues to adjust to Armour Thyroid, expect dizziness to decline in intensity and possibly subside altogether.

Facial puffiness: A limited number of Armour Thyroid users have reported facial puffiness or swelling.  If you notice that your face has become puffy, this could be a sign of an allergic reaction and/or issue with your dosing.  It could also be that Armour Thyroid is causing increased retention of watery fluid within your facial tissue.

This side effect may decrease over time and/or if your dosage is optimally adjusted.  However, it may be an unappealing side effect if considering your physique.  If the facial puffiness isn’t significant, you may be able to put up with it, but if severe, it may compromise your self-esteem and possibly lead to depression.

Fatigue: A majority of Armour Thyroid users notice that after several weeks of administration, their overall energy level has significantly improved.  Unfortunately, a subset of users experience the side effect of increased fatigue, lethargy, and somnolence – to a greater extent than pre-hypothyroidism treatment.  Feeling more fatigued during treatment than you did living with untreated hypothyroidism is a problem.

Assuming your thyroid levels have normalized with Armour Thyroid, yet you still feel excessively fatigued, a doctor may recommend switching to levothyroxine (or another intervention).  If you plan on continuing Armour Thyroid, yet don’t know how you’ll cope with the fatigue, adjunctive medications such as eugeroics and/or psychostimulants may prove beneficial.  Talk to your doctor about the severity of your fatigue and possible strategies that could be used to improve your energy level.

Fingernail chipping: Nearly all interventions for hypothyroidism have propensity to affect the strength of fingernails.  You may notice that your fingernails become increasingly brittle, chip more than usual, appear wavy, or even completely fall out.  It is unclear exactly how Armour Thyroid affects a person’s fingernail strength, but it is important to recognize this as a potential side effect.  Some individuals report that their fingernails appear discolored or all-around unhealthy while using Armour Thyroid.

Hair loss: Among the most common side effects of Armour Thyroid treatment is hair loss.  Most users will experience some hair loss and/or hair thinning during the first few months of treatment.  After several months of treatment, hair loss tends to diminish and/or subside altogether.

Losing your hair may take a toll on your self-image, but it is a necessary side effect associated with nearly all treatments for hypothyroidism.  The amount of hair that Armour Thyroid users are likely to lose is subject to individual variation and may be related to drug dosing.  If hair loss persists after a long-term of treatment, switching medications may be a logical solution.

Headaches: Another extremely common side effect of Armour Thyroid is headaches.  Most people experience mild to moderate headaches when initiating treatment (e.g. in the first several months).  As a patient adjusts to Armour Thyroid and continues treatment, the severity of headaches typically tends to diminish and/or subside.

A small percentage of users may report ongoing headaches throughout their entire term of treatment.  Unless you are experiencing an array of additional side effects along with headaches and/or unbearable migraines, headaches may be a side effect that some users simply accept as part of treatment.  Decreasing tension with relaxation exercises and/or co-administration of anti-inflammatory agents may prove helpful.

Hot flashes: Don’t be surprised if you experience hot flashes while taking Armour Thyroid – this is a side effect reported by many users.  Increased levels of thyroid hormone can affect thermoregulatory processes within the body, thereby increasing your chances to experience brief, sudden feeling of increased heat.  You may notice that hot flashes cause flushing of the face, sweating, and/or lead to chills.

While some hot flashes are common, especially in early phases of treatment, ongoing severe hot flashes may warrant an adjustment in dosing and/or change of treatment.  If you’re experiencing constant, severe, long-lasting hot flashes throughout the day, Armour Thyroid could be the culprit.  Talk to your doctor about ways in which you can decrease likelihood of hot flashes as a side effect.

Insomnia: It is understood that hypothyroidism can cause individuals to sleep excessively.  Treatment with Armour Thyroid often decreases the likelihood of excess sleep by increasing energy levels.  Although many people find that their sleep schedule normalizes with Armour Thyroid, others find that treatment can induce insomnia and interfere with the ability to transition from wakefulness to sleep.

During treatment, you may lie down to fall asleep, but find it nearly impossible to quiet your mind and/or slow your thinking.  It may feel as if your thoughts are rapid, uncontrollable, and as if you feel abnormally anxious and/or stimulated – making it difficult to fall asleep.  If the insomnia is caused by Armour Thyroid, your doctor may consider a dosing adjustment, medication change, and/or adjunctive prescription (e.g. a hypnotic).

Irregular heartbeat: Throughout treatment with Armour Thyroid, it is especially important that you monitor your heartbeat.  Armour Thyroid may cause your heart to beat abnormally rapid or irregularly.  You may also notice heart palpitations or fluttering and/or loud beating of the heart.

Sometimes irregular heartbeats and palpitations can be triggered by anxiety and/or increases in physiological arousal.  That said, if you suspect that Armour Thyroid may be detrimentally affecting your heart function, a thorough cardiac evaluation may be necessary.  Monitoring the heart throughout treatment is especially important among those who are at risk for cardiovascular disease and/or have a history of cardiovascular events.

Jitteriness: Some individuals feel extremely jittery when they first start taking Armour Thyroid.  This jitteriness tends to subside as their physiology adjusts to the drug, but also diminishes as dosing is properly calibrated.  That said, jitteriness may be a byproduct of heightened anxiety and/or neurophysiological stimulation associated with treatment.

If you feel increasingly restless, unable to sit still, or are shaky – Armour Thyroid could be the cause.  You may want to consider switching to another treatment and/or talk to your doctor about how to cope with the constant jitters that you’re feeling on this medication.  Certain individuals may find that a co-administered drug or supplement helps reduce Armour Thyroid-induced jitteriness.

Joint pain: Among the most popular side effects of Armour Thyroid is joint pain.  The joint pain may result from swelling of the joints and/or changes in bone density throughout treatment.  At high doses, Armour Thyroid (and other thyroid interventions) are known to decrease bone density and may reduce muscle tissue – each of which could cause a user to perceive that he/she is weaker and/or has joint problems.

Some patients may benefit from a change of medication if the joint pain is deemed severe.  Joint pain resulting from Armour Thyroid may be related to increases in inflammation and/or fluid retention.  Talk to your doctor about ways in which you can reduce medication-induced joint pain such as via anti-inflammatory agents, pharmaceuticals, or supplements.

Menstrual changes: It is no secret that women notice changes in their menstrual cycle after taking Armour Thyroid.  Hypothyroidism is associated with exceptionally heavy periods (increased bleeding), and when reversed with Armour Thyroid, periods often become lighter.  It is common to notice less bleeding while taking Armour Thyroid than you had experienced in a hypothyroid state.

Additionally, women have reported substantial changes in the timing of their menstrual cycle while taking Armour Thyroid (compared to pre-treatment).  Specifically, women may report increased time between periods while using Armour Thyroid and greater unpredictability (or variance) in menstruation times.  As the dosage of Armour Thyroid is properly calibrated and the body adapts to treatment, menstrual irregularities may normalize.

Mood swings: Low thyroid is known to cause depression, but high thyroid can cause significant anxiety.  That said, even if thyroid levels (T4/T3) are normalized with Armour Thyroid treatment, there’s no guarantee that mood will remain stable.  Some individuals experience noticeable negative mood swings throughout treatment with feelings of: anger, anxiety, depression, and irritability.

Individuals with preexisting neuropsychiatric disorders may be more likely than others to experience mood swings from Armour Thyroid treatment, however, the side effect of mood swings does not solely occur among those with neuropsychiatric conditions.  If you begin taking Armour Thyroid and notice that your mood worsens, is unpredictable, and you feel miserable – discuss this with your doctor.  It may take a dosing adjustment or change of treatment to improve your mood.

Nausea: Another side effect reported by many Armour Thyroid users is nausea.  Experiencing nausea is most common in the early weeks and/or months of treatment when the body hasn’t fully adapted to Armour Thyroid and/or the dosage hasn’t been properly adjusted by a medical professional.  For most users, nausea tends to diminish and/or subside altogether after the initial few months of treatment.

If the nausea is of moderate and/or severe intensity, talk to your doctor about possible ways in which you can cope with it.  Sometimes a simple change in Armour Thyroid dosing can significantly reduce and/or decrease nausea.  However, if the nausea is severe enough as to provoke vomiting and/or severely reduce your appetite, a switch to a different medication may be warranted.

Nervousness: Feeling a bit more nervous than usual is another reported side effect of Armour Thyroid.  Some Armour Thyroid users notice that they feel nervous in situations that were previously relaxing (e.g. hanging out with friends) and dislike this side effect.  Although the nervousness may not be severe, it may be somewhat bothersome for certain users, especially those with preexisting anxiety disorders.

In some cases, too high of an Armour Thyroid dosage may be contributing to nervousness.  In other cases, the dosage of Armour Thyroid may be considered optimal, but the individual may exhibit supratherapeutic levels of T3 (triiodothyronine) which could contribute to feeling nervous, jittery, anxious, etc.  If the nervousness is a major concern, a medication change and/or adjuvant anxiolytic may provide therapeutic benefit.

Restlessness: A side effect that some individuals notice during treatment with Armour Thyroid is restlessness.  The side effect of restlessness may be accompanied by anxiety, jitteriness, nervousness, or even agitation.  You may find it impossible to sit still or feel as if you constantly need to move while taking Armour Thyroid due to significant increases in energy (possibly caused by supraphysiological concentrations of T3).

In some cases, restlessness may be more likely to occur during the first few weeks of Armour Thyroid treatment and/or among those taking too high of a dose.  As your body adjusts to the influx of porcine-derived hormones, restlessness may gradually subside.  However, if the restlessness doesn’t subside, you may need to cope by: going for a walk, relaxation exercises, and/or with administration of an anxiolytic.

Seizures: An extremely rare (yet reported) side effect of Armour Thyroid is seizures.  Those that have been medically diagnosed with epilepsy or have previously experienced a seizure may be at greatest risk of an Armour Thyroid-induced seizure.  It is unclear exactly how Armour Thyroid may provoke seizures, but some speculate that it may (directly or indirectly) alter neuroelectrical (brain waves) activity and neurochemistry.

The combination of neuroelectrical and neurochemical alterations could prompt a seizure among someone diagnosed with epilepsy.  Likelihood of experiencing a seizure may be reduced by starting with the low dose and titrating upwards to the optimal amount.  Seizures may be most likely to occur among those that have ingested a supratherapeutic dose and/or intentionally overdosed.

Sensitivity to heat: A commonly reported Armour Thyroid side effect is heat sensitivity.  It is well-understood that thyroid levels affect thermoregulatory processes within the body, leaving many hypothyroid patients to feel constantly chilled and/or cold.  During treatment with Armour Thyroid, you may have the exact opposite experience: feeling excessively and/or abnormally warm; some users may even run a low-grade fever.

Some speculate that the increased heat sensitivity is a result of blood flow changes and BMR changes elicited by Armour Thyroid.  By elevating concentrations of T4/T3 with Armour Thyroid, the body’s BMR (basal metabolic rate) increases and is burning more energy at rest than usual.  Burning more energy at rest results in greater generation of heat, thereby making the person feel “hotter” than average and sensitive to warm environments.

In addition, Armour Thyroid may also make your skin feel warmer than usual from increased blood flow.  If you find yourself walking into average-temperature rooms, constantly seeking out cold, and/or wondering if someone “turned up the heat” – it’s probably a side effect of Armour Thyroid.  Heat sensitivity is especially common among those taking too high of an Armour Thyroid dose.  To decrease likelihood of this side effect, be sure you are taking the lowest effective amount.

Shortness of breath: An adverse reaction associated with Armour Thyroid is shortness of breath.  If you are experiencing shortness of breath from this treatment, it should be discussed immediately with a medical professional.  Shortness of breath may be a sign of a serious cardiac reaction (e.g. heart attack) or an underlying cardiovascular disease.

Assuming you have undergone a thorough cardiovascular evaluation via a medical professional (e.g. cardiologist) and are considered “healthy,” then the shortness of breath may be a benign reaction or a sign of Armour Thyroid-induced anxiety.  Shortness of breath may be more common among those taking higher-than-necessary dosages due to the excessive stimulation associated with supraphysiological concentrations of T4/T3.  If the shortness of breath is severe and interferes with your well-being, administration of an adjunct anxiolytic or medication change may be warranted.

Sleep disturbances: Many individuals taking Armour Thyroid experience sleep disturbances as a result of treatment.  In addition to experiencing insomnia, many individuals note that they wake up frequently throughout the night and/or feel as if they aren’t getting “deep sleep.”  If you feel as if Armour Thyroid is affecting your sleep quality or preventing you from getting enough sleep (quantity), a review of your current dosing may be necessary.

Assuming your hormonal biomarkers are optimized, yet your sleep is still disturbed as a result of treatment, you may want to talk to your doctor about a safe adjunctive sleeping medication (Z-drug) or herbal hypnotics.  Realize that sleep disturbances are most common in the early weeks/months of Armour Thyroid treatment and often subside thereafter.  That said, if your sleep quality remains poor after a significant duration of treatment – you may want to consider other thyroid medications.

Sweating: Countless Armour Thyroid users report profuse sweating as a side effect of this treatment.  It may be that elevations in T4/T3 resulting from Armour Thyroid treatment activate sweat glands throughout the body to a greater extent than usual.  As a result of increased sweat gland activation, you may find yourself sweating: round-the-clock (24/7), throughout your entire work/school day, and/or throughout the night.

Since elevations in thyroid levels with Armour Thyroid can increase BMR, the body is burning more energy at rest and generating more heat – possibly leading to sweat.  Additionally, increased blood flow throughout the skin may lead users to feel warmer than usual and begin to sweat excessively.  Some users are willing to put up with mild/moderate sweating as a side effect, but extreme sweating may warrant switching to another intervention.

Tremors: During the initial few weeks of treatment, you may find yourself shaking or experiencing tremors from Armour Thyroid.  Since shakiness is a side effect that can occur as a result of excessive thyroid (hyperthyroidism), you may want to review your current dose and/or dosing instructions with a medical professional.  Tremors may also be a sign of an adverse allergic reaction to Armour Thyroid.

Many individuals report transient, uncontrollable tremors in the extremities such as the fingers, hands, and legs.  Usually the tremors resulting from Armour Thyroid are caused by lack of precise dosing.  If your dosage has been properly calibrated by a doctor and tremors remain bothersome, discuss alternative thyroid treatments and/or an anxiolytic to reduce the physical shakes.

Vision changes: An unfortunate side effect reported by some Armour Thyroid users is blurred vision and/or changes in visual perception.  If you had perfect vision prior to taking Armour Thyroid, yet feel as if your eyesight is deteriorating and/or your visual acuity is reduced during treatment, realize that this is a side effect.  The changes in vision may stem from alterations in neural activation, particularly within the visual cortex – as induced by Armour Thyroid.

It is not always easy to accept visual changes as a side effect of treatment because you may believe that Armour Thyroid is legitimately damaging your eyes.  To ensure that no actual damage occurs as a result of Armour Thyroid treatment, you may want to regularly monitor your vision with an ophthalmologist.  If the blurred vision is significant, you may want to discuss alternative thyroid treatments with your doctor.

Weight changes: Many individuals taking Armour Thyroid end up experiencing weight changes.  If you had severe hypothyroidism prior to taking Armour Thyroid, normalization of thyroid levels should increase your BMR and give you more energy for physical activity – each of which contribute to weight loss.  Evidence from published research suggests that Armour Thyroid users are likely to notice some modest weight loss after 4 months of treatment.

A small percentage of users report weight gain during Armour Thyroid treatment.  Weight gain may be a more common side effect among those experiencing increased appetite, fatigue, and/or sleeplessness as a result of Armour Thyroid.  Weight fluctuations may also be influenced by dietary choices and/or concomitantly administered medications.  (For more information read: Armour Thyroid & Weight Loss).

Note: It is important to note that Armour Thyroid side effects are subject to significant interindividual variation.  Most users will not experience every single side effect on the above list.  Some individuals may experience zero noticeable side effects whatsoever (this is ideal).  If you have any questions or concerns about a particular side effect that you’re experiencing, talk to your doctor.

Why side effects may occur with Armour Thyroid

There are a few reasons that side effects may be more likely with Armour Thyroid than other interventions.  Although many consider Armour Thyroid equally as tolerable as synthetically manufactured formulations, others believe that it may actually be less tolerable.  Reasons side effects and adverse reactions may be likely among Armour Thyroid users include: T4/T3 ratios, lack of clinical trials, inter-batch variability, and/or formulation changes by pharmaceutical companies.

  1. T4:T3 ratio (4:1)

In humans, the ratio of T4 (thyroxine) to T3 (triiodothyronine) is considered 11:1.  In other words, there is 11x the amount of thyroxine (on average) in a healthy human compared to triiodothyronine.  Although Armour Thyroid corrects thyroid deficiencies, it is a desiccated thyroid extract derived from pigs which produce a 4:1 ratio of T4 to T3.

Some researchers believe that Armour Thyroid may elevate T3 to supraphysiological levels, thereby increasing occurrences of side effects and adverse reactions.  Obviously you’ll want to receive thorough thyroid panels throughout treatment with Armour Thyroid to know whether your T3 level is abnormally high.  If your T3 is elevated too significantly, Armour Thyroid may pose tolerability issues.

  1. Lack of FDA approval

Unlike synthetically engineered thyroid replacement therapies (e.g. synthroid), Armour Thyroid has not gone through rigorous clinical, randomized controlled trials.  Its long-term safety and efficacy aren’t well-established in humans.  Since desiccated thyroid extract is “natural” and was around before the FDA regulatory process, it remained on the market for sale, yet may be lacking in terms of safety.

For this reason, some speculate that there may be more side effects experienced among Armour Thyroid users than FDA-approved agents.  Some research has been conducted, but none involving clinical trials.  The lack of FDA approval may be a major “red flag” among endocrinologists and medical doctors.

  1. Inter-batch variability

It is possible that there is inter-batch variability in Armour Thyroid based on the pigs from which the desiccated thyroid extract was collected.  Extracts taken from one set of pigs may be significantly (or even slightly) different than those from another set of pigs.  Differences in specific pigs from which thyroid extracts were collected may affect the quality of the product.

Patients have long speculated that a “bad batch” of Armour Thyroid can cause side effects.  If certain side effects are batch-dependent, it may be that inter-batch variability is the culprit.

  1. Formula alterations

Many patients believe that the formula of Armour Thyroid has been altered, and as a result, its efficacy has diminished.  Some individuals that had been taking the older formulation manufactured by Forest Laboratories reported that it simply “stopped working” when they tried the newer formulation manufactured by Actavis.  It is possible that pharmaceutical companies make slight tweaks to the Armour Thyroid ingredients in attempt to maximize profits.

Unfortunately, despite the fact that certain ingredient adjustments may not appear to alter efficacy of Armour Thyroid, many patients notice that the drug stops working.  If you experienced side effects and/or a decrease in the efficacy of Armour Thyroid after using the Actavis version, it may have been a result of the formula change.

Variables that influence Armour Thyroid side effects

It was already mentioned that not every individual taking Armour Thyroid will experience the same specific side effects.  Additionally, the overall number of side effects and their respective severities will be subject to variation based on interindividual variables.  These variables that influence side effects include: Armour Thyroid dosage, duration of administration, co-administered drugs/supplements, specific dosing instructions, and genetics.

  1. Dosage (Sensitivity)

Individuals taking too high of an Armour Thyroid dose are more likely to experience side effects than those taking a properly adjusted dose.  As with any thyroid replacement therapy, there is a narrow therapeutic index (NTI) associated with Armour Thyroid dosing.  This means that a very precise dosage should be prescribed based on specific hormonal biomarkers of patients (e.g. T4, T3, FTH).

If the dosing is imprecise and a person with hypothyroidism receives an excessive amount of Armour Thyroid, levels of T4 and T3 may be abnormally high and TSH may abnormally low.  The greater the extent to which your dosage of Armour Thyroid exceeds the neurophysiological (hormonal) requirements of your body, the greater the likelihood you are to experience side effects.  On the other hand, if you’re taking too low of a dose, you may be less likely to experience side effects, but more likely to remain in a state of hypothyroidism.

A precisely calibrated dosage of Armour Thyroid should optimize hormonal biomarkers while simultaneously minimizing likelihood of side effects.  Side effects and adverse reactions should be considered most common among individuals taking a suboptimally high dose for their particular condition.  Recalibration of dosing by a medical professional often corrects Armour Thyroid-induced side effects.

  1. Duration of administration

The duration over which you’ve been taking Armour Thyroid can influence the severity and number of side effects that you experience.  Those that have been taking Armour Thyroid for a short duration are more likely to experience side effects than those who’ve been taking it for a moderate and/or long-term.  However, in some cases, new side effects may emerge over the long-term that had not occurred over a short or moderate term.

Short-term:  Short-term users are more likely to experience unwanted side effects for two major reasons.  Firstly, when administered over the short-term (e.g. weeks), it will not be immediately apparent whether the perfect Armour Thyroid dosage has been administered.  It can take months before a doctor has figured out the proper dosage of the drug for a patient’s particular neurophysiology.

Secondly, the body will not have had enough time to adapt to the presence of Armour Thyroid over a short-term.  Although it is considered “natural” it is still exogenously administered and a user’s neurophysiology will need to adjust to its regular administration.  Since it often takes months for a full adjustment to take place, side effects are often noticeable over the short-term.

Moderate-term: After a moderate-term of use, Armour Thyroid users may notice that some short-term side effects have diminished in intensity or subsided.  For example, you may notice that after several months, the hair loss caused by the drug stops.  You may also find that other side effects such as: blurred vision, sleep disturbances, and/or weight changes have ceased.

Side effects often diminish after several months of treatment not only because the body has adapted to the presence of Armour Thyroid, but because the dosage will have been properly adjusted (perhaps multiple times).  As the adjusted dosage alters concentrations of T4, T3, and TSH within therapeutic ranges – side effects are likely to decrease.  Additionally, after a moderate-term, some users discover ways in which they can cope with and/or treat side effects from Armour Thyroid.

Long-term: Most long-term Armour Thyroid users don’t report significant side effects for numerous reasons.  Individuals that take Armour Thyroid for a long-term generally are able to tolerate it well compared to other options.  Had Armour Thyroid caused significant and/or intolerable side effects, it would’ve likely been discontinued and another medication would’ve been pursued.

In addition, long-term users have also gone through the entire neurophysiological adjustment phase in which their body and brain adapted to the Armour Thyroid.  Upon adaptation of the presence of Armour Thyroid (over an extended duration), many side effects will have abated.  Moreover, the combination of sustained physiologic adaptation and precisely calibrated dosing will result in fewer side effects for long-term users than short or moderate term users.

  1. Co-administered agents

If you’re experiencing side effects while taking Armour Thyroid, it may be necessary to consider whether you’re taking any other drugs and/or supplements along with it.  If you are taking other drugs or supplements on a daily basis along with Armour Thyroid, have you considered that they themselves could be causing many of your side effects?  Some individuals may mistakenly chalk up the side effects they’re experiencing to Armour Thyroid, when in fact they are from an entirely different medication.

It is also possible that various other drugs and/or supplements that you’re taking could be interacting with the pharmacokinetics or pharmacodynamics of Armour Thyroid.  In other words, certain substances if taken along with Armour Thyroid may affect its absorption and/or distribution.  Other agents may serve to potentiate the effects of Armour Thyroid such as by increasing neurophysiological arousal, synergistically causing side effects such as: anxiety, insomnia, and/or weight loss.

On other hand, certain drugs or supplements may offset various side effects of Armour Thyroid.  For example, someone taking a beta-blocker for hypertension may find that it offsets certain side effects of Armour Thyroid such as irregular heartbeat, profuse sweating, and nervousness.  If you have questions about whether a particular agent is interacting with Armour Thyroid, ask a medical professional.

  1. Adherence to dosing instructions

Armour Thyroid is recommended to be taken on an empty stomach, at least 30 to 60 minutes prior to breakfast.  Additionally, it is instructed to be taken at the exact same time each day without any other drugs or supplements (as these could affect its absorption or cause an adverse reaction).  If you misinterpreted dosing instructions (as given by your doctor) or haven’t been following them precisely, you may be more likely to experience side effects.

Someone who adheres strictly to dosing instructions will reduce his/her odds of severe and/or unwanted adverse effects.  If you’re experiencing adverse reactions from Armour Thyroid, you may want to review how carefully you’ve been following the guidelines for dosing.  Talk to your doctor and/or a pharmacist if you have any questions about how Armour Thyroid should be administered.

  1. Genetics

It is reasonable to consider that genetic (and possibly epigenetic) expression can affect how a person responds to Armour Thyroid.  Although this is a natural thyroid hormone, not everyone is able to tolerate it equally well.  Some individuals experience severe, burdensome, ongoing side effects throughout treatment that never subside and/or diminish, while others experience no significant unwanted side effects.

While differences in side effects can often be explained by aforestated variables such as: dosage, duration of administration, co-administered substances, and adherence to dosing instructions – sometimes there are no major differences in these variables between users – yet side effects differ considerably.  For this reason, is likely that specific genes affect how well a person can tolerate Armour Thyroid.  If you’re able to tolerate Armour Thyroid extremely well, it could be a result of your genes.

Armour Thyroid: Do the benefits outweigh the side effects?

If you’re taking Armour Thyroid, it is necessary to track whether the therapeutic benefits associated with treatment outweigh the side effects.  A subset of users will notice nothing but therapeutic benefits from Armour Thyroid without any noticeable (or severe) side effects.  Assuming you’re reaping considerable benefits without debilitating or functionally-impairing side effects, continued treatment is a relatively easy decision.

Most users of Armour Thyroid will experience a combination of therapeutic benefits and mildly unpleasant side effects.  Assuming you experience mild side effects such as appetite changes, upset stomach, and/or slight hair thinning – yet your thyroid levels optimized by the treatment – you’ll likely have no problem putting up with these reactions.  Mild side effects are usually significantly outweighed the the Armour Thyroid treatment.

It may be more difficult to decide whether you should continue treatment if you’re experiencing equally debilitating side effects as benefits.  You may feel your energy level has improved and you’re losing some weight, but you may also notice increases in anxiety, hair loss, and sleep disturbances.  In this case, it may be worth talking to your doctor about adjunct strategies to reduce these side effects and/or testing other treatments.

Finally, a small percentage of users will report that the side effects significantly outweigh any benefits.  Some individuals may find that although Armour Thyroid normalizes their thyroid levels (according to hormonal biomarkers), they feel no benefit from treatment and/or experience side effects such as hair loss, mood swings, diarrhea, and/or nausea.  In this case, it may be wise to consider pursuing an alternative hormone replacement therapy to Armour Thyroid.

You may find it beneficial to document your experience of Armour Thyroid treatment within a journal.  Journaling allows you to take a snapshot of how you’re feeling each day with treatment, as well as side effects you’ve been putting up with.  After a month or two, you can reflect on the bigger picture (side effects vs. benefits) over an extended period of time and decide whether you’d like to continue with Armour Thyroid or try something else.

Possible ways to reduce Armour Thyroid side effects

If you’re experiencing major unwanted side effects from Armour Thyroid, it may be helpful to consider some side effect mitigation strategies.  Ways in which you may be able to reduce side effects include: readjustment of dosing, review of dosing instructions, adding adjunctive medications, eliminating other drugs/supplements, and/or continue using Armour Thyroid.  Prior to implementing any of these side effect mitigation strategies, verify safety and practicality with a medical professional.

  1. Readjust dosage: If you’re experiencing unwanted side effects, it’s possible that you’ve been prescribed too high (or low) of an Armour Thyroid dose. Suboptimal dosing is especially common among those that have been taking Armour Thyroid for a short duration (e.g. less than a few months). Talk to your doctor about rechecking your hormone levels and readjusting your Armour Thyroid dose.  You may find that a slight adjustment in dosing makes a significant difference in lessening side effects.
  2. Review dosing instructions: In some cases, users of Armour Thyroid experience side effects because they aren’t carefully following dosing instructions. Administration of Armour Thyroid after eating food and/or with another medication may cause side effects. Talk to your doctor about when to take Armour Thyroid (e.g. prior to breakfast) and how long you should wait before taking other medications (or supplements).
  3. Adjunctive options: Sometimes side effects may persist even after optimizing your dosage and carefully following dosing instructions. Certain side effects such as sleeplessness and anxiety can often be managed safely with adjunct pharmacological interventions. Discuss the safety and efficacy of an adjunct to offset and/or help you cope with side effects of Armour Thyroid.
  4. Elimination: Although some individuals may benefit from an adjunctive intervention (to treat side effects), others may benefit even more from elimination of an unnecessary drug and/or supplements. Certain substances may potentiate certain neurophysiological effects of Armour Thyroid. This could exacerbate side effects such as: anxiety, mood swings, and/or insomnia.  Work with your doctor to eliminate unnecessary medications and/or supplements from your regimen to determine whether side effects improve.
  5. Continued usage: If you’ve only been taking Armour Thyroid for a short-duration, side effects are likely. With continued usage, your doctor will evaluate your thyroid levels and optimize your Armour Thyroid dosage to reduce future likelihood of side effects. Additionally, as you continue treatment, your neurophysiology may adapt to regular administration of the Armour Thyroid, and as a result, certain side effects may abate.

Have you experienced Armour Thyroid side effects?

If you’ve experienced side effects while taking Armour Thyroid, leave a comment below.  Mention the specific side effects you found most debilitating and discuss their severity (e.g. on a scale of 1 to 10).  To help others get a better understanding of your situation, share some details such as: your dosage of Armour Thyroid, the condition you’re treating, how long you’ve been taking it, and whether you use other medications and/or supplements.

In your particular case, do you believe that the benefits associated with Armour Thyroid outweigh unwanted side effects?  Understand that although Armour Thyroid is considered “natural,” this doesn’t automatically mean it’s well-tolerated by all users.  If you’re struggling with severe side effects from Armour Thyroid, it may be wise to evaluate other hormone replacement options.

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{ 7 comments… add one }
  • elsa martin March 12, 2016, 10:24 pm

    I’m allergic to all thyroid meds. With armour, I got severe shortness of breath, jitteriness, restless, swollen in my neck, in my belly, anxiety, itchy in my face. I dropped it, was feeling worse and worse. Took it for almost 3 months. My throat felt tight and swollen, I got scared. Was feeling better without it.

  • Pam May 23, 2016, 11:50 pm

    Taking Armour thyroid for 5 weeks. Rashes, itching all over, tightening of my throat and my skin feel like it is on fire. My lips are swollen, eyes scratch and swollen almost shut. I am stopping the meds ASAP as Benydryl is not stopping the allergic reactions I am having. I feel like I have been dipped in mace. My throat and neck are sore, and I have blotches especially on my neck. My face looks sunburned. Is this normal?

  • Shannon August 10, 2016, 1:18 pm

    I have experienced swelling in my hands and serious joint pain. I reduced the dosage and the swollen hands and pain have gotten better, but still not great. I said my joints were hurting and I thought it was from the Armour dosage and suddenly I had to be tested for RA… So, I cut the pills myself and am seeing a difference, so I know I’m on the right track. Very frustrating that the Dr had no idea joint pain could be a side effect.

  • Deb August 20, 2016, 5:11 pm

    I’ve been on Armour Thyroid for 8 months from Forest Labs. This morning, I got up to run 18 miles as part of my marathon trying and ended up in the ER after taking Armour. The last 2 weeks’ dosage is from Actavis labs. My skin was on fire with hives on my head, neck, arms, legs and groin are. I had to receive epinephrine, Benadryl and a steroid to make it stop. I don’t know if there was a formulation change that did this but I’m switching back to Synthroid until I can get in to see my doctor.

  • Julie C September 4, 2016, 8:00 pm

    I am switching back to Synthroid tomorrow… Since I have been on Armour, I have been extremely irritable, I have been in bed with 102 degree fever, nausea, dizziness, and feeling very intolerant to the heat. This is so awful, because I wanted to spend this 3-day weekend with my family and now am unable to enjoy it because of how awful I feel.

  • Sarah Galt October 1, 2016, 3:02 am

    Have had increased swelling in joints and am trying to figure out if it is my arthritis or if it is related to switching to Armour Thyroid. I have shown intolerance to bacon and am wondering if the source of Armour Thyroid (pig) is causing the inflammation. Would love to know if anyone knows anything about this. Sarah

  • Elodia October 5, 2016, 1:59 am

    I’ve only been on Armour for 2 weeks and I am so tired. Tried taking at night and I am still exhausted. Also irritable and anxious. Didn’t have problems with Synthroid, will have to see my doc again. ;o(.

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